Aug 4, 2010 - detection by the bathymetric profile of the ocean and self-noise of the ... underwater projectors. Tonpilz (German for âsinging .... impedance matching device. 1-3 Piezocomposite Transducer Arrays Receiver. Inset: Projector. 08. V ol.
flight control software for various. UAVs in general helps in the following main functions: Automated launch phase. Manual and assisted take-off and landing (Rustom). Manual flying. Heading hold, altitude hold, speed hold and track hold functions. Ai
task of displaying certain information. But when it ... and XML are so popular, for information display and ... computer is using for example, Visual Basic on a.
Feb 2, 2014 - systems to handle the auto CAD, SolidWorks, CATIA V5, and DELMIA DPM assembly software to generate virtual. CAD models, assembly ...
Oct 5, 2011 - faced at high altitude and are one of the essential items to be included in the ration of Defence Forces, specifically ... lemon munch, and ajwain munch. The animal studies and human trials have found ... high altitude (Leh) have been c
Multimedia is a combination of text, graphics, animation, audio and video, converted from ... everlasting impact on publishing. Slowly all these recording media, used for storing. In '940s .... songs, movies, genealogical works, etc. LC brought ...Mi
Sep 22, 2007 - (RSS), E-mail forums, online office, personal web learning, shared videos, video online and .... A wiki invites all users to edit any page or to.
Abstract: Laser communication links in space are attractive alternatives to ... between free-space optical links on one hand and glass fiber systems and ...
Dec 30, 2015 - 10, No. 2, 264â277 (2016) / DOI 10.1002/lpor.201500186. ORIGINAL PAPER. Abstract An analytical model is presented describing the tem-.
Apr 22, 2015 - Technology (NITs) between February1-28, 2015, by using a checklist. The results of this study revealed that the majority of NIT library websites ...
the taxonomy of reference sources .... well as a number of other web resources. (j) Question Point .... Another limitation is the difficulty to multitask during a.
Periodically poled lithium niobate (PPLN)-based frequency doublers and mixers enable efficient second- (66%) and third- (35%) harmonic generation from the ...
Aug 9, 2002 - into an adaptive optics system a 351 nm Rayleigh laser guide star ... sufficient power to adequately excite the sodium resonance line ... special air-conditioned room on the observatory ground floor ..... troller. The rotating disk cont
Traditional power supplies cannot be used for driving a ... diode. A typical voltage source does not offer the level of cur- ... the center of a typical benchtop experi-.
(AMS Web Site, 180W setting). 0.2 - 0.4 mm. (Quanta System testing;. EAU Guidelines on Lasers and ... a deeper coagulation zone and necrosis risk compared to either holmium or thulium laser systems. .... the surgeon to wear bright-orange laser safety
Center for Athletic Medicine; Kevin Rand, ATC, CSCS, Head Athletic Trainer ... sporting activities, but frequently foot placement and ... For the best treatment.
DRDO sponsored NATIONAL CONFERENCE ON CONTROL, COMMUNICATION AND SYSTEM. ENGINEERING ... system with iris and fingerprint as a computer application for ..... authentication technology for controlling door access in a.
used to model battlefield scenarios where multiple entities sense and ..... in mind that merely because an agent-based model mimics a battlefield entity ...
Long range missiles need high transmit power ... replica of transmitter carrier as far as phase and frequency ..... link is 4 Mbps use linear FM technique.
Oct 23, 2017 - services in the Indian context is the presence of a poor telecommunication .... March-April 2016. Using MS Excel the ... Homepage length, language, look and feel ... Source: Author's calculation based on data collected table 4.
Interesting relationships have been found between refractive index, plasmon energy, electronic .... when the difference of the electronegativities of the two species is equal or more than about 0.2 units, small amounts of ionic bonding may take.
access techniques, the principle of mobile satellite communication and finally the brief mention of presently .... Ã°/4âQPSK Modulation: Recently Ã°/4âQPSK & Ã°/4.
InteractiVenn tool13. HPTLC analysis was carried out using an assembly from CAMAG, Switzerland. Chemometric studies were conducted using the software R: ...
ISSN : 0971-4413
Facilities Thermal/Electron beam evaporation
BULLETIN OF DEFENCE RESEARCH & DEVELOPMENT ORGANISATION
Dual ion beam sputtering In-situ film thickness monitor Taly step surface profiler Nomarski differential interference contrast Microscope with CCTV and camera
LASER SYSTEMS DEVICES & MATERIALS
For more information please contact: The Director LASTEC Metcafe House Delhi-110 054 Ph : 91-11-23817625 Fax: 91-11-23811319
Technology Focus highlights the technological developments in DRDO, and also covers the products, processes and technologies.
Editorial Committee Coordinator Dr Mohinder Singh, Director, DESIDOC, Metcalfe House, Delhi Members Shri Ajai Kumar, Director of Aeronautics, Sena Bhavan, New Delhi Dr Harihar Singh, Director of Armaments, Sena Bhavan, New Delhi Dr JP Agrawal, Director of Materials, Sena Bhavan, New Delhi Shri A Bhagavathi Rao, Director of Electronics, Sena Bhavan, New Delhi Shri Gopal Bhushan, SO to SA to RM, South Block, New Delhi
Editorial Staff Editors
Design & Pre-press
Ashok Kumar, Vinod Kumari
JV Ramakrishna, SK Tyagi
Readers of Technology Focus are invited to send their communications to the Editor, Technology Focus DESIDOC, Metcalfe House, Delhi - 110 054. India Telephone: 011-23819975; Fax: 011-23819151; Drona-mail: [email protected] E-mail: [email protected], [email protected] Internet: http://www.drdo.org/pub/index.shtml; http://www.drdo.com/pub/index.shtml Printed & published by Dr Mohinder Singh, Director, DESIDOC, on behalf of DRDO. RNI No. 55787/93
Special Editor Shri KS Jindal Director, LASTEC Metcalfe House Delhi-110 054
From the Desk of the Special Editor
Diode Pumped solid-state Laser
LASER is an acronym for light amplification by stimulated emission of radiation. During the last few decades, lasers have unquestionably become an important part of science and technology with wide ranging applications. The specific properties of lasers have been exploited both for military as well as civilian applications. Some of the important applications include laser weaponary; measurement and inspection; information storage and retrieval; communication; remote sensing; bio-medical applications such as ophthalmology, dermatology, tumor therapy, dentistry; and manufacturing operations such as cutting, welding, and surface treatment; etc.
DRDO has developed a highly compact and robust passive Qswitched diode pumped Nd:YAG laser system. It generates 5 [email protected] pps power output in 20 ns that leads to the development of ultra-compact, high repetition-rate laser systems for various military applications like target designation and range finding. The system combines advantages of both diode pumping and passive Q-switching techniques. It is simple and modular in design than its conventional counterparts with a separate laser head, and laser diode driver modules of 4.2 cm x 8.2 cm x 16.4 cm and 7 cm x 8.3 cm x 26 cm size, respectively. Driver is one of the critical components of the overall diode pumped solid-state laser system due to the
The development of various aspects of lasers right from components, materials up to a dedicated system have been the thrust area of Defence Research & Development Organisation, for the last more than a decade now. Laser work at DRDO was initially started way back in 1970, when the development of solid-state lasers, viz., Ruby and Nd:YAG was taken up. The Ruby crystals were grown in-house during the seventies. In eighties, laser range finders and designators based on Nd:YAG were developed for various applications. DRDO has also done pioneering research work in the field of electro-optic countermeasure (EOCM) laser systems and has successfully developed state-of-the-art anti-sensor laser systems indigenously.
design complexities involved in delivering high peak current pulses with desired rise time, overshoot and droop characteristics. Its soft start feature protects the vulnerable diode arrays from power on transients and ensures safe and reliable operation of the system. It operates from a 12 V battery power pack, which is an integral part of the driver package and occupies about one-third of the package volume. The system can be operated in both single shot and repetitive mode of 10 pulses/s, respectively.
Drishti DRDO has successfully developed prototype of Nd:YAG photodisrupter eye care laser system, which can be used for post cataract care and glaucoma treatment. Lightweight, low cost, simple operation, easy maintenance, conical and direct aiming/focusing system, dual He-Ne laser aiming beam, Ziess type slit-lamp microscope, and Nd-YAG laser directly retro fitted on SLM treatment beam are some of the important features of Drishti.
This Special Issue of Technology Focus highlights some of the laser systems, devices and materials developed by DRDO.
The prototype of Drishti has been successfully tested at National Institute of Ophthalmology, Pune, K.E.M. Hospital, Mumbai, and Sankara Nethralaya, Chennai. The technology has been transferred to Bharat Electronics, Pune.
Cryogenic Cooling System
Waveguide CO2 Laser
A Joule-Thomson-based cryogenic The radio frequency (RF) excited CO2 waveguide lasers, in various power ranges
cooling system for cooling imaging
and slab channel configuration with packaged electronics and unstable resonator,
infrared (IIR) seeker has been
are used for Defence applications. A major breakthrough has been achieved with the demonstration of a compact, portable, and battery-operated 20 W
developed. The system meets the requirements of 1 W of heat load
CO2 waveguide laser in packaged configuration as well as in unstable
at a temperature of 80 + 1 K.
resonator configuration with near symmetrical output beam
Three such cryogenic cooling
geometry. Packaged version of hard sealed 20 W laser is nearing
systems have been successfully
developed and integrated in Nag missile carrier (NAMICA). The system has undergone track trails, roadability trails in different terrain and also under o high temperature (50 C) desert conditions.
Optical Parametric Oscillator The use of laser range finders in fire control systems has greatly increased the accuracy and effectiveness of modern day weapon systems. The laser range data, fed to the fire control computer, has not only reduced the firing time but also increased first round hit capabilities. Most of the laser range finders present today are based on Nd:YAG/Nd:Glass lasers operating at a wavelength of 1064/1054 nm, which is extremely harmful to the human eye. The eye-safe laser operating at around 1540 nm has the highest permissible ocular exposure accepted by the ANS 2 l2.136.1-1993 standard (1 J/cm for single pulses whose widths range from 1 ns to 10 s). The concern for safety and the need for realistic training tactics has necessitated the use of an eye-safe laser. Also, the recent changes in modern combat scenarios of urban warfare have made the need for eye safety mandatory. One of the most promising state-of-the-art techniques for eye-safe lasers is based on nonlinear optical technique. DRDO has successfully developed and demonstrated the generation of eye-safe wavelength by optical parametric oscillator (OPO) technique. Eye-safe wavelength was generated from an OPO employing a nonlinear crystal pumped by Nd:YAG laser operating at 1.064 µm. The system has generated output energy of 18 mJ on initial experimentation in a pulse width of 25 ns giving a conversion efficiency of more than 35 per cent, which is likely to be upgraded to 50
A cooling system for Nag missile check out vehicle has also been developed and integrated on the 7.5 ton stallion vehicle as well as on advanced light helicopter.
LASER DEVICES Dual Role Electro-Optic Countermeasure In the present day war scenario, extremely sophisticated technology oriented weapon systems are being developed for potential combat advantage. Conventional optical instruments have given way to electro-optic (EO) sensors and lasers for precise guidance of munitions to maximise effectiveness. The electro-optic countermeasure (EOCM) class of lasers integrated with a suitable laser threat detection system can be an effective means to address this threat scenario.
per cent conversion efficiency through further optimisation in the near future. The technique is being configured into an engineered system for user application.
Keeping in mind the widespread use of EO devices by most of the advanced countries, DRDO has also developed a dual wavelength (dual role) EOCM system for anti-sensor as well as dazzling applications. The system is built around a
Dual wavelength EOCM system
frequency-doubled Q-switched Nd-YAG laser and generats 2J/pulse output power at 1064 nm for anti-sensor role and 1J/pulse output power at 532 nm for dazzling role, respectively. It is modular in construction and can be configured for various vehicular platforms.
Laser Threat Warner An ultra-compact laser threat warner has been developed, which is capable of giving warning in the form of an audio beep as well as a visual indication, when the user of the gadget is exposed to a laser radiation. It is capable of detecting visible or near IR laser threats from existing and emerging battlefield pulsed solid-
Threshold Detector A threshold detector unit has been developed for evaluation of EOCM class of solidstate laser systems over long ranges in field conditions. Such detector is not available commercially in the format desirable for long-range diagnostic application. It has selectable energydensity threshold levels and is capable of establishing whether the energy density at the desired target point is above or below the preset threshold level.
and EOCM class of solid-state lasers (dazzlers, anti-sensor
The unit gives both an audio and a visible indication when the energy density at the target point
EOCM lasers systems, etc.). The laser warner can be
is more than the set value. It can be used with both
sported by a soldier to take an evasive action in the event of
free running as well as Q-switched type of pulsed
state lasers such as laser range finders, laser designators,
solid-state lasers. It has a wide measurement range
getting exposed to hazardous laser radiation.
offering three possible range selections of 5 J/cm to
The gadget, with slight modification, can be adapted to
multiple sensor configurations, which gives it a broad
The unit has been tested in the field with both types of lasers covering pulse energy range of
sectors. A helmet mounted multiple sensor system, with four
less than a joule to kilo-joule level and has auto shut-off facility after 15 s to enable firing of multiple
laser sensors mounted on the helmet spaced 90 apart would provide 360
levels at each range setting.
direction sensing capability in the form of pre-defined
50 J/cm , 5 mJ/cm to 50 mJ/cm and 5 J/cm to 50J/cm with availability of 10 selectable threshold
shots. It is battery operated and needs no human intervention at the target point.
battlefield coverage. The multiple sensor
configurations would particularly suite the armoured vehicles, combat vehicles and other similar ground platforms used in a mechanised environment. o
Ultra-Compact Electronics Package for High-Energy Flash Pumped Solid-state Lasers
The laser threat warner, in the present form, has a wide field of view of greater than 150 , made possible due to innovative front-end design. The gadget covers a spectral band of 400 nm to 1100 nm and is capable of distinguishing between low PRF (tank range finders) and high PRF (laser designators) laser threats. It operates on a 9 V DC battery and can be configured to operate on 20 to 32 V DC. This ultra-compact (120 mm x 80 mm x 35 mm) laser threat warner is a total indigenous effort, both in design and implementation. All components used are easily available within the country. The gadget has been extensively Soldier with laser warner
tested in the field ranges in excess of 3 km.
An ultra-compact electronic package (180 mm x 180 mm x 70 mm) for high-energy flash lamp pumped solid-state laser has been developed. The unit has an output power delivery capability of 1000 J/s and employs a completely new DC to DC converter topology (patent filed) that gives it flexibility to use any energy/pulse repetition rate combination. This new topology also allows the designer to use a wide range of energy storage capacitor (5 µF to 200 µF) and charging voltage (500 V DC to 1500 V DC) to get the desired energy without compromising any of its features. It also gives 10 J/s or 1000 J/s or even 10 kJ/pulse output power at 100 PPS, 1 PPS, and at 0.1 PPS, respectively with the same ease and efficiency without any design modification. The design also allows the user to connect the individual units in parallel for enhancing its output power delivery capability. The charging unit, the heart of the system, has a conversion efficiency of more than 90 per cent and has been packaged in a size and weight that is about 60 per cent of the size and weight of similar units with comparable specifications from leading international manufacturers of laser power supplies.
The package has been extensively
Development of IO components and
evaluated by interfacing it with an
devices require cleaning of substrates,
appropriate flash lamp used in Nd-
spin coating, exposure and development
YAG/Nd-Glass laser systems and optical
time, and titanium coating thickness and
pumping established at 10 J/Pulse at 100
diffusion time. Channel waveguide is the
PPS. The input pumping energy here is
basic building block of any IO device.
typical of a designator class of laser
DRDO has developed a channel
systems. The development is particularly significant as the non-lethal class of laser weapons including EOCM class lasers, which are invariably going to be high-energy pulsed solid-state lasers, are projected to proliferate the future battlefield.
waveguide-based polarise by spin coating
DRDO has established core competence in developing compact electronics packages for high-energy pulsed solid-state lasers of the non-lethal laser weapon category, and capability to develop 100 PPS class laser designators. The electronics package of such systems predominantly governs the size, weight and efficiency of the overall system.
DRDO has facilities for testing of channel waveguide-based polariser phase modulator, and directional couplers.
of 5 mm width on LiNbO3 wafer. The polarise has extinction ratio of TM mode with respect to TE ~24db/cm. Channel waveguide-based phase modulator, and directional coupler (1 x 2) have also been developed.
Integrated Optics Integrated optics (IO) has emerged as a frontline, state-of-the-art technological area for the generation, manipulation, transmission and use of light information by providing compact, efficient and reliable components and devices. Systems based on IO technologies have high bandwidth capabilities, are not affected by electromagnetic interference, and are faster than the fastest silicon chip-based electronic systems.
Fine line lithographic facility
LASER MATERIALS The solid-state lasers are playing increasingly important role in the present day warfare. Heart of these lasers is the host material. The host material can be either single crystal or laser glasses. The future laser systems will employ laser diodes (LD) pumping for various applications. The systems based on LD pumping are highly efficient, compact, rugged and have long life. The crystals like Nd:YVO4, and disordered garnet crystals such as Nd:CNGG can achieve better efficiency than Nd:YAG in diode pumped laser systems due to their better absorption characteristics. Of the two crystals, CNGG is very economical. The Nd:YVO4 is most ideally suitable material for LD pumping.
Crystal Growth DRDO has developed facilities and expertise for the growth of single crystal for laser and nonlinear optical (NLO) applications using Czochralski and solution techniques. Some of the 3+ important crystals grown by using Czochralski technique are Ruby (Cr :Al2O3), Lithium Niobate (LiNbO3), Lithium Tantalate (LiTaO3), Neodymium-doped Calcium Niobium Gallium Garnet
DRDO has expertise and facilities for the synthesis of Neodymium-doped phosphate laser glasses, small scale melting of special optical glasses, and treatment of solid materials at elevated temperature.
(Nd:CNGG), and Bismuth Silicate (Bi12SiO20). Synthesis of feed materials and growth parameters of these materials have been fully established and optimised.
DRDO is also developing Erbium-Ytterbium-Chromium-Neodymium-doped phosphate laser glasses for eye-safe laser range finders operating at 1.540 µ wavelength. The work is in the advance stage of development.
Devices like Q-switch, Bragg Cell, and transducers have been fabricated using LiNbO3 crystals grown in-house. The LiTaO3 crystals were used for the fabrication of pyroelectric detector.
The large size (4 cm x 4 cm x 11cm)
Optical thin film coating is an essential
Potassium Di-hydrogen Phosphate (KDP)
activity for any optical or EO system used for
crystals and its deuterated isomorphs have
sighting, aiming, and ranging purpose. DRDO
been grown using solution technique. The
has acquired the state-of-the-art expertise in
development of highly efficient and damage
the design of various types of optical thin films. It
Inorganic single crystal
resistant NLO crystals, viz., L-Arginine
offers standard thin film and special coatings for
Phosphate (LAP) crystal of large size (4 cm x 4 cm x 1.5 cm) is one of the important achievement of the DRDO in the field of NLO crystals. The second harmonic generation of Nd:YAG with conversion efficiency of 11 per cent and 35 per cent for KDP and LAP, respectively have been achieved.
optical components and systems for vision instruments, lasers, other scientific and medical research applications. The details of coatings, substrate and facilities that can be provided is
The geometry laser systems are used in pulsed laser range finders, material processing, and medium-and high-power laser systems. DRDO has developed Neodymium-doped YAP (Yttrium Aluminium Phosphate), and high Neodymiumconcentrated KBAP (Potassium Barium Aluminium Phosphate) laser glasses for the geometry laser systems.
Ion beam sputtering unit
Laser mirrors for sophisticated laser systems Antireflection coatings Beam splitters (laser line/broadband) Interference filters (BWHH ~50 Å ) Metal coated mirrors (R ~99.9 per cent) Beam combiners
The developed YAP and KBAP laser
Coatings to specification
glass rods of 6 mm diameter x 75 mm length have low threshold for laser action (less than
15 J), high slope efficiency (1.5 per cent), high stimulated emission cross-section (4 cm 2
x 10-20 cm ), and longer fluorescence life time (290 µs). Both have extremely good optical quality and are water resistant. The YAP laser glass is cost effective and has potential of replacing YAG in low-repetition rate laser systems. The KBAP laser glass is being used in indigenous slab geometry